FIELD OF THE INVENTION
The present invention relates to a rail apparatus around a nuclear reactor pressure vessel and, more particularly, to a rail apparatus on which a device such as an inspection device is carried to more along the surface of the reactor pressure vessel in the vertical and the circumferential directions.
For inspecting the surface of the reactor pressure vessel with, for example, an ultrasonic flaw detector, the ultrasonic flaw detector is movably carried on rails laid around the surface of the reactor pressure vessel to detect any flaw existing in the surface of the same.